I've just heard that the organisers have apologised. Not good enough, I'm afraid. This event cost £24 or £26 to enter in advance. Many people will have travelled and paid for overnight accommodation - they will not all be local. I had an event cancelled on me on the day (because of predictable weather conditions) and it cost me about £100. Organisers have to show some respect to the runners. There is nothing wrong with tap water, and as everyone else is saying the community could have got together and got that sorted.
Suggest you go onto the Weston Running Promotions website - below is an exerpt from it. There is contact e-mail address on the site.
In 2000 to celebrate The Millennium, eight of the team assisted John organise “The Island Race” – the first ever relay run around the coastline of Britain – 4,500 miles in 100 days raising over £1million for various charities.
It has been done before - it was done in 2000 carrying a message for the Queen or something. It got difficult around Dover apparently as it was quite dangerous on the roads and no alternative. On that occasion there were lots of runners doing bits each or in groups.